Charge forming device having a constant level device



Aug. 2, 1966 TAO-YUAN wu 3,263,975

CHARGE FORMING DEVICE HAVING A CONSTANT LEVEL DEVICE Filed Dec. 50, 1963Iii-9;;

7:40 YUAN WU v INVENTOR.

ATTOR/VIYS United States Patent 3,263,975 CHARGE FORMING DEVICE HAVING ACQNSTANT LEVEL DEVICE Tao-Yuan Wu, Ann Arbor, Mich, assignor to FordMotor Company, Dearborn, Mich., a corporation of Delaware Filed Dec. 30,1963, Ser. No. 334,268 2 Claims. (Cl. 261-70) This invention relates toa charge forming device for an internal combustion engine and moreparticularly to a constant level device for maintaining a uniform fuelhead in a fuel bowl of the charge forming device.

The fuel metering circuits of most conventional charge forming devicesrely upon a uniform fuel head for effective operation. A float operatedvalve generally i provided to maintain a consistent fuel level in thefuel bowl in a conventional charge forming device. The fuel in the fuelbowl of a charge forming device of a motor vehicle, however, issubjected to external forces that cause the fuel level to changeartificially without a significant change in the total volumn of fuel.For example, during acceleration, deceleration, operating on inclines orrounding curves, the fuel level is temporarily disturbed. Under theaforementioned conditions the float operated valve may either openprematurely or remain closed longer than is desirable. Premature openingof the valve will cause a surplus of fuel to flow into the inductionpassage of the engine with attendant flooding whereas delayed opening ofthe valve will cause fuel starvation. Each condition, therefore, resultsin unsatisfactory engine operation.

It is, therefore, the principal object of this invention to provide afloat operated valve for a charge forming device that is relativelyinsensitive to temporary disturbances in the fuel level as are caused byvehicle operation.

It is a further object of this invention to provide a float operatedvalve that provides a substantially uniform head of fuel above a mainmetering jet in a charge forming device fuel bowl regardless of externalforces acting upon the charge forming device.

A charge forming device embodying this invention has a fuel bowl, aninduction passage and fuel discharge circuit means for discharging fuelfrom the fuel bowl into the induction passage. A fuel inlet is providedin the fuel bowl and a valve member controls the admission of fuel fromthe fuel inlet into the fuel bowl. A float is buoyantly supported by thefuel in the fuel bowl. Lever means operatively connect the float to thevalve member for moving the valve member between an opened and a closedposition upon movement of the float in a first plane. The float isfreely movable upon the lever means in another plane without affectingthe position of the valve member.

Further objects and advantages of this invention will become moreapparent when considered in conjunction with the accompanying drawings,wherein:

FIGURE 1 is a cross sectional view taken along the axis of an inductionpassage of a charge forming device embodying this invention.

FIGURE 2 is a cross sectional view taken along the line 22 of FIGURE 1.

FIGURE 3 is a cross sectional view taken along the line 33 of FIGURE 1.

FIGURE 4 is a perspective view of the float supporting lever assembly.

Referring now in detail to the drawings, the body portion of a chargeforming device embodying this invention is identified generally by thereference numeral 11. The body portion 11 contains a fuel bowl 12 and aninduction passage 13 having a venturi section 14. A throttle valve 15 isrotatably supported by a throttle valve shaft 16 Patented August 2, 1966in the lower portion of the induction passage 13. A cover plate 17 isafiixed to the body portion 11 in a suitable manner Wtih a gasket 18interposed therebetween. The cover plate 17 extends across the fuel bowl12 adjacent to an integral air horn portion 19. The air horn portion 19forms an air inlet passage 21 that registers with the induction passage13 in the body portion 11.

A main metering jet 22 having a calibrated orifice 23 is positioned inthe lower surface of the fuel bowl 12 along the vertical center of thecharge forming device. The main metering jet 22 is positioned at themouth of vertically extending passage 24 formed in the body portion 11below the fuel bowl 12. The passage 24 terminates at a passage 25 thatextends upwardly and transversely through the body portion 11 to a mainfuel well 26. A booster venturi nozzle assembly 27 is affixed to thebody portion 11 with a small discharge venturi 28 positioned in theinduction passage 13 contiguous to the main venturi section 14. Fuel andair metering tubes 29 and 31 depend into the main fuel well 26 from thebooster venturi nozzle assembly 27. Fuel is discharged from the mainfuel well 26 into the induction passage 13 by the nozzle assembly 27 ina known manner.

A tapped hole 32 is formed in the body portion 11 at one side of thefuel bowl 12 above the normal fuel level. A fuel inlet fitting 33 isthreaded into the tapped hole 32 with a gasket 34 positioned between thebody portion 11 and an enlarged portion 35 of the inlet fitting 33. Fuelis introduced under pressure from a fuel pump (not shown) through a fuelpassage 36 that extends through the inlet fitting 33. The fuel passage36 terminates at a restricted portion 37 formed adjacent a bore 38 thatextends into the fuel bowl 12. A needle valve 39 having flattened sides40 is slidably received in the bore 38. The needle valve 39 has atapered surface 41 that is adapted to contact the restricted portion 37to preclude the flow of fuel into the fuel bowl 12. When needle valve 39is axially spaced from the restricted portion 37 fuel may flow into fuelbowl 12 through the clearance between flattened sides 40 and the bore38.

The needle valve 39 is actuated by a float assembly, indicated generallyby the reference numeral 42 to provide a uniform head of fuel in thefuel bowl 12 above the main metering jet 22. The float assembly 12includes a float 43 that is buoyantly supported by the fuel in the fuelbowl 12. The float 43 is supported for pivotal movement with respect tothe body portion 11 along two pivotal axes by a lever assembly shown ingreater detail in FIGURE 4.

The lever assembly includes a lever having a horizontally extendingfirst part 44 that terminates at a vertically extending second part 45.The vertically extending second part 45 terminates at a horizontallyextending third part 46 that is parallel to the first part 44. The thirdpart 46 extends through a cylindrical bushing 47 formed in the float 43below its center of buoyancy in the gasoline in the fuel bowl 12. Snaprings 48 and 49 axially locate the float 43 upon the third lever part 46and permit pivotal movement of the float 43 upon the lever part 46. Thelever part 46, therefore, determines a first pivotal axis of the float43.

A cylindrical part 511 of a sheel metal bracket receives a pin 52. Thecylindrical part 51 has an upturned tab 53 formed with an aperture 54that receives the outer end of the first lever part 44. The first leverpart 44 is secured within the upturned tab 53, as by a weld 55. The pin52 is journaled in arcuate slots 56 and 57 formed in the body portion 11adjacent the outlet opening of the bore 38. The lever and float 53 mayrotate with the pin 52 to form a second pivotal axis for the float 43.Pivotal movement of the float 43 about this axis is transmitted intomotion of the needle valve 39. For this purpose, the tab 53 contacts anarcuate head 58 of the needle valve 39. The normal fuel pressure in thepassage 36 will urge the needle valve 39 against the tab 53.

As fuel is discharged from the fuel bowl 12 into the induction passage1'3, the level of fuel in the fuel bowl 12 will be depleted. This causesthe float 43 to pivot in a clockwise direction about the pivotal axisdefined by the pin 52. Pivotal movement about this axis causes the tab53 to move away from the inlet fitting 33. The fuel pressure acting onthe needle valve 39 urges the needle valve 39 toward the tab 53. Thetapered surface 4 1 of the needle valve 39 is then moved away from therestricted portion 37 of the inlet fitting 33 and fuel is permitted toflow into the fuel bowl 12 until the float 43 returns to the preselectedheight. When this occurs, the needle valve 39 will be again moved int-ocontact with the restricted portion 37 and preclude the flow of fuelinto the fuel bowl 12.

It should be readily apparent that under certain conditions the level offuel in the fuel bowl may be disturbed Without a change in the volume offuel in the fuel bowl. Such a change in level is represented by thebroken line in FIGURE 2. When this condition occurs in a norm-a1 chargeforming device the float has a tendency to raise or fall, depending uponthe geometry of the system. Movement of the float in the conventionalcarburetor will be transmitted into movement of the needle valve 39 tocause a change in the fuel volume within the fuel bowl 12. This willcause either starvation or flooding of the engine. In a carburetorembodying this invention, however, the float 43 may pivot about its axison the third lever portion 46 to the dotted line position shown inFIGURE 2. This pivotal movement of the float 43 does not cause anymovement of the needle valve 39. It is additionally noted that thepivotal axis defined by the third lever portion 46 lies in substantiallythe same vertical plane as the orifice 23 of the main metering jet 22.The level of fuel above the main metering jet 22 will 4 thus berelatively unaffected by the displacement of the fluid.

It is to be understood that this invention is not limited to the exactconstruction shown and described, but that various changes andmodifications may be made without departing from the spirit and scope ofthe invention, as defined by the appended claims.

I claim:

L A charge forming device comprising a body having a fuel bowl and aninduction passage,

a fuel inlet into said fuel bowl,

valve means movably positioned in said fuel inlet,

a float adapted to be buoy-antly supported by fuel in said fuel bowl,

a lever positioning said valve means to control fuel flow through saidfuel inlet, said lever being pivotally connected to said float about asubstantially horizontal first axis below the center of buoyancy of saidfloat, means pivotally mounting the lever about a second axis at a rightangle to the first axis for moving the valve means, and

a fuel outlet from said fuel bowl for discharging fuel into saidinduction passage.

2. The charge forming device of claim 1 in which the float has a singlecylindrical bushing mounted therein, said bushing being located in thevertical plane that contains the center of buoyancy of said float, andthe lever is pivotally located in said bushing.

References Cited by the Examiner UNITED STATES PATENTS 1,168,783, 1/1916 Bucker.

1,270,213 6/19'18 Roesch r l37-434 X 2,430,719 l'l/1947 Johnson et al.l374-34 X 2,729,436 1/ 1956 Norris 26172 X 3,071,354 1/1'963 Newman261-72 X HARRY B. THORNTON, Primary Examiner.

R. R. WEAVER, Assistant Examiner.

1. A CHARGE FORMING DEVICE COMPRISING A BODY HAVING A FUEL BOWL AND ANINDUCTION PASSAGE, A FUEL INLET INTO SAID FUEL BOWL, VALVE MEANS MOVABLYPOSITIONED IN SAID FUEL INLET, A FLOAT ADAPTED TO BE BUOYANTLY SUPPORTEDBY FUEL IN SAID FUEL BOWL, A LEVER POSITIONING SAID VALVE MEANS TOCONTROL FUEL FLOW THROUGH SAID FUEL INLET, SAID LEVER BEING PIVOTALLYCONNECTED TO SAID FLOAT ABOUT A SUBSTANTIALLY HORIZONTAL FIRST AXISBELOW THE CENTER OF BUOYANCY OF SAID FLOAT, MEANS PIVOTALLY MOUNTING THELEVER ABOUT A SECOND AXIS AT A RIGHT ANGLE TO THE FIRST AXIS FOR MOVINGTHE VALVE MEANS, AND A FUEL OUTLET FROM SAID FUEL BOWL FOR DISCHARGINGFUEL INTO SAID INDUCTION PASSAGE.